# conway.r
# Thomson Nguyen
# tn248@cam.ac.uk

# Simulates Conway's Game of Life
# size: the length of our starting matrix (a size^2 square)
#
# MIT License blah blah blah
#
# Directions:
# 1. Run script
# 2. Press enter to timestep
# 3. Breaks on non-blank input.

size <- 200
grid <- FALSE

matrix <- matrix(round(c(runif((size^2)))),nrow=size)

nrows <- dim(matrix)[1]
ncols <- dim(matrix)[2]

squaresize <- 60/max(c(nrows+1,ncols+1))

left = c(2:nrows,1)
right = c(nrows,1:nrows-1)
up = c(2:ncols,1)
down = c(ncols,1:ncols-1)

k = ""
# stop on keypress
while (nchar(k) == 0){
	matrix.neigh <- matrix[,up] + matrix[left,] + matrix[,down] + matrix[right,] + matrix[left,up] + matrix[left,down] + matrix[right,up] + matrix[right,down]

# Conway's rules
	mnew = matrix
	mnew[(matrix==1 & matrix.neigh <= 1) | (matrix==1 & matrix.neigh >= 4)] <- 0
	mnew[matrix==0 & matrix.neigh==3] <- 1
	matrix = mnew

	m1 <- which((matrix==1),arr.ind=TRUE)
	if (grid == TRUE) m0 <- which((matrix==0),arr.ind=TRUE)

# plot time
	plot(NA,xlim=c(0,ncols),ylim=c(nrows,0),xlab="",ylab="")
	points(m1[,c(2,1)],cex=squaresize,bg="blue")
	if (grid == TRUE) points(m0[,c(2,1)],pch=22,cex=squaresize)
	k <- scan(what = "character",nmax = 1,quiet=TRUE)
	k <- paste(k,"",sep="")
}